氧化物混合粉原位反应制备超细WC-Co复合粉的研究

研究了WO3、Co3O4和碳黑混合粉经高能球磨后在真空炉中还原和碳化生成WC-Co复合粉的工艺过程。结果表明：高能球磨时间对混合粉末粒径、复合粉纯度和尺寸有重要影响;超细混合粉具有高的反应活性,使反应在较低温度下完成;制备的复合粉细小均匀,无杂相,平均粒径约300nm。本文提出的真空条件下一步还原碳化获得超细WC-Co复合粉的创新技术路线对改进传统技术长周期制备WC-Co复合粉,进而显著节省资源和能源具有十分重要的意义。     

片式电阻浆料用钌酸铅粉的制备

以超细氧化钌粉、氧化铅为原料,选用特定的焙烧工艺和球磨工艺,利用固相合成法,并通过烘干和破碎处理得到了粒度分布较窄、性能稳定的粉末,满足了片式电阻浆料的使用要求。采用湿法激光粒度仪测试钌酸铅粉的粒度分布与平均粒径,用扫描电子显微镜(SEM)分析钌酸铅粉的形貌、粒径和团聚状态,用X射线衍射仪(XRD)检测粉体的晶相。并简要讨论了影响钌酸铅粉制备过程的各类因素。     

高能球磨Al-Y203粉体固相反应制备YAG陶瓷的研究

用高纯Al粉体和Y2O3粉体(Al-Y2O3粉体)为原料采用固相反应法制备了YAG陶瓷. Al-Y2O3粉体高能经过球磨,煅烧生成YAG粉体,再真空烧结制备高致密YAG陶瓷.采用DTA-TG对球磨Al-Y2O3粉体进行分析,采用XRD、SEM对球磨的Al-Y2O3粉体、YAG粉体及YAG陶瓷进行了表征.实验表明:Al-Y2O3粉体在～569℃时,Al粉强烈氧化,并与Y2O3粉反应,600℃煅烧出现YAM相,随煅烧温度升高出现YAP相,1200℃煅烧生成YAG粉体.成型YAG素坯在1750℃保温2h真空烧结出YAG相陶瓷,YAG陶瓷相对密度可达98.6%,晶粒生长均匀,晶粒尺寸为8～10μm.     

高能球磨Al-Y2O3粉体固相反应制备YAG陶瓷的研究

用高纯Al粉体和Y₂O₃粉体(Al-Y₂O₃粉体)为原料采用固相反应法制备了YAG陶瓷. Al-Y₂O₃粉体高能经过球磨, 煅烧生成YAG粉体, 再真空烧结制备高致密YAG陶瓷. 采用DTA-TG对球磨Al-Y₂O₃粉体进行分析, 采用XRD、SEM对球磨的Al-Y₂O₃粉体、YAG粉体及YAG陶瓷进行了表征. 实验表明: Al-Y₂O₃粉体在～569℃时, Al粉强烈氧化, 并与Y₂O₃粉反应, 600℃煅烧出现YAM相, 随煅烧温度升高出现YAP相, 1200℃煅烧生成YAG粉体. 成型YAG素坯在1750℃保温2h真空烧结出YAG相陶瓷, YAG陶瓷相对密度可达98.6%, 晶粒生长均匀, 晶粒尺寸为810μm.     

高纯钨单晶坯料预处理工艺探讨

制备高质量的钨单晶的一个前提条件是坯料的纯度水平,而预处理则是决定坯料纯度的重要工序.本文探讨了三种预处理工艺,讨论了不同工艺方法对熔炼稳定性、间隙杂质纯化作用方面的影响,证明采用高纯APT经还原、高温烧结、电子束熔炼预处理工艺,可有效降低间隙杂质元素含量,保证区域熔炼过程的稳定性,制备出材质优良,性能稳定的高纯钨单晶产品.     

杂质离子对非晶态水合氧化钌电化学超电容性能的影响

采用化学沉淀法(在RuCl_3溶液中滴加NaOH)制备非晶态水合氧化钌,用去离子水对非晶态水合氧化钌沉淀充分洗涤,获得了Na、Cl杂质含量不同、而非晶态结构、水含量和显微相貌都相同的两种氧化钌样品.X射线光电子能谱分析表明,样品中的Na和Cl杂质分别以水合Na~+、水合Cl~-的形式存在.去离子水充分洗涤5次的样品(W-5)与不充分洗涤1次的样品(W-1)相比,前者的Na~+、Cl~-杂质含量低.循环伏安测试表明,W-5的比电容和功率性能都优于W-1 Na~+、Cl~-杂质不仅降低了氧化钉的比电容,也降低了氧化钌的功率性能.在非晶态水合氧化钌的制备过程中杂质含量的控制对获得高超电容性能十分重要.文中还分析了Na~+、Cl~-杂质对电容性能不利影响的机理.     

钙钛矿型BaZrO3纳米粉体的制备及表征

采用辅助凝胶法制备BaZrO₃纳米粉体，探究不同原料比、不同煅烧温度、真空气氛对BaZrO₃纳米粉体的制备、晶粒尺寸、微观形貌等方面的影响规律。结果表明：在原料中摩尔比Ba∶Zr=1.1∶1,空气下1100℃+空气650℃煅烧条件下，可以得到纯的BaZrO₃纳米粉体，且晶粒尺寸约为90.8nm;真空气氛下得到的BaZrO₃纳米粉体晶粒尺寸更小，约为42.8nm;制备过程简单高效，所得产物纯度高，粒径小且粒度分布窄，有望应用于其他纳米陶瓷粉体的制备。     

烧结温度和粉末预处理对SPS制备超细晶硬质合金的影响

采用亚微米WC粉和微米Co粉混合粉末作为原料,利用高能球磨与放电等离子烧结(SPS)技术制备超细晶WC-10Co硬质合金.研究表明,球磨后直接烧结时,当温度由1150℃增加到1200℃,试样的晶粒尺寸和硬度没有明显变化(平均晶粒尺寸约250nm),但致密度提高至98.6%,横向断裂强度由1045MPa提高到1819MPa.当对球磨后的混合粉末进行900℃真空处理后,在较低温度烧结的条件下试样的致密度则高达99%,且横向断裂强度与未处理粉末在相同工艺下烧结获得提高.     

高纯金属镝的制备

为制备高纯度稀土金属Dy以适应高科技发展的需求,在钙热一次还原法生产的Dv-4,Dv-8的基础上,用中频感应炉进行二次精炼和真空蒸馏,并对工艺进行优化选择得出,二次精炼温度为1450℃,保温40 min最适宜;真空蒸馏1 500℃～1 530℃,保温8 h最佳.用此工艺所制备的金属Dy的纯度超过国标高纯度Dv-1和Dv-2的要求,接近国外高纯Dy的先进技术指标.     

纳米晶SnO2粉末的制备

采用常规溶液化学沉淀法,通过仔细控制沉淀速率以类独石状Ｓｎ（ＯＨ）４沉积物。采用两种不同的煅烧工艺制备ＳｎＯ２粉,即：常规的将沉淀物磨成粉末后煅烧和将灰独石状沉淀物直接煅烧。选取４５０、６００,７５０。９００和１０５０℃个温度条件,保温２ｈ煅烧。结果表明直接煅烧法得到的ＳｎＯ２粉末的晶粒平均尺度较常规煅烧工艺得到的ＳｎＯ２粉末（１２￣５０ｎｍ）小,从晶化动力学角度对该现象给予了解释。     

Metal Injection Moulding Using Intermetallic γ‐TiAl Alloy Powder

Argon gas atomized γ‐TiAl alloy powder of high purity has been used for metal injection moulding. In order to keep the pick‐up of impurities as low as possible most of the process steps were done under inert gas or high vacuum. The binder system used had been especially developed for titanium alloys. In the sintered structures the nitrogen and carbon levels are low, oxygen scatters over a wide range. The porosity of ∼4 % after sintering could be reduced to ∼0.4 % by additional hot isostatic pressing. Tensile tests at room temperature indicate promising properties of σ_0.2 = 409 MPa, UTS = 433 MPa and ϵ_pl = 0.6 %.     

Zr_2P_2WO_(12)/Fe-Ni复合材料的制备及其热膨胀性能研究

使用水热法成功制备Zr_2P_2WO_(12)粉末,采用真空热压烧结方法制备接近致密的Zr_2P_2WO_(12)/Fe-Ni复合材料。使用X射线衍射、扫描电镜及热膨胀测试仪对制备的Zr_2P_2WO_(12)及其Fe-Ni复合材料进行性能测试和表征,使用维氏硬度计测试复合材料的硬度,使用排水法表征复合材料的密度。结果表明:水热法制备的Zr_2P_2WO_(12)粉为高纯度的单相Zr_2P_2WO_(12),颗粒规则,晶粒尺寸约为50nm;随Zr_2P_2WO_(12)含量的增加,Zr_2P_2WO_(12)/Fe-Ni复合材料的硬度增加,而密度和致密度则降低,在25~800℃区间内平均热膨胀系数从13.5×10~(-6)/℃降低到8.6×10~(-6)/℃。     

Recent progress in the preparation of nuclear targets at IAE

The development and study of the preparation of nuclear targets at IAE since 1979 are described. Targets of several elements and enriched isotopes have been made by reduction distillation in vacuum or by electroplating. Furthermore, methods such as rolling, centrifugal precipitation, electrospraying, and focused heavy-ion beam sputtering have been set up. An α-particle thickness gauge and a high sensitive quartz thickness gauge have been installed. Rutherford backscattering has been applied successfully to the determination of the thickness and the impurity content of target layers.     

ITO靶材高温真空热压炉的研制

本文介绍了稀有金属行业ITO靶材高温真空热压炉的设备组成、主要技术参数和结构特点,并指出了该设备在稀有金属行业ITO靶材制造行业推广应用的前景.     

Formation of Branched Ruthenium Nanoparticles for Improved Electrocatalysis of Oxygen Evolution Reaction

Branched nanoparticles are one of the most promising nanoparticle catalysts as their branch sizes and surfaces can be tuned to enable both high activity and stability. Understanding how the crystallinity and surface facets of branched nanoparticles affect their catalytic performance is vital for further catalyst development. In this work, a synthesis is developed to form highly branched ruthenium (Ru) nanoparticles with control of crystallinity. It is shown that faceted Ru branched nanoparticles have improved stability and activity in the oxygen evolution reaction (OER) compared with polycrystalline Ru nanoparticles. This work achieves a low 180 mV overpotential at 10 mA cm^?2 for hours, demonstrating that record‐high stability for Ru nanocrystals can be achieved while retaining high activity for OER. The superior electrocatalytic performance of faceted Ru branched nanoparticles is ascribed to the lower Ru dissolution rate under OER conditions due to low‐index facets on the branch surfaces.     

溅射钽靶材用高纯钽粉工艺研究

分析了高纯钽粉生产的技术特点,介绍了一种改进的钽靶材用高纯钽粉的生产方法。采用高温脱氢(900~950℃)和低温脱氧(700~800℃)分步进行的工艺,有利于钽粉氧、氢、镁含量及粒度的控制,所得样品兼具低氧和小粒度的特点。采用真空热处理(700~800℃)工艺可以有效除去脱氧后残余的金属镁、酸洗带入的H、F等杂质,确保颗粒不长大,同时使杂质含量得到了很好的控制。     

透明氮化铝陶瓷的制备

本文采用碳热还原法制得的ＡｌＮ粉,使用烧结剂ＣａＣ２,热压制备了透明氮化铝陶瓷,实验证明,纯度高、粒径料小、且均匀的ＡｌＮ粉是制备透明ＡｌＮ陶瓷的必要条件。ＡｌＮ陶瓷从紫外,可见光到近红外均透明,显微结构研究表明,ＡｌＮ陶瓷透明是由于晶粒完整规则,紧密排列,晶界干净,而气孔、晶粒内和晶界第二相杂质、缺陷是影响透明度的原因。     

Process methodology for the small scale production of m6N5 purity zinc using a resistance heated vacuum distillation system

Ultra high purity Zn (m6N5) was obtained through triple vacuum distillation using an m4N5 Zn as input material. High-volatile impurities were removed from the zinc matrix by vacuum evaporation, while traces having lower volatility than the matrix remained in the residual material after finishing of the entire purification process. The time required for the removal of the main high-volatile impurity (Cd) was monitored using a connected gas source mass spectrometer. During distillation the Zn vapor of the distillate was condensed on the cap of a glassy carbon crucible which was water cooled by a movable copper block. The temperatures were optimized for the removal of the volatiles and for the distillation process using vapor pressure data. High resolution glow discharge mass spectrometry was applied for the analysis and purity evaluation of the distilled and input zinc. The analysis confirmed the reduction of the metallic impurities from 43 mg kg⁻¹ to 0.5 mg kg⁻¹ (m6N5) after three consecutive vacuum distillations. An increase in the grain size and a decrease in the micro-hardness were observed for the purified Zn material.     

HOT PRESSING OF DIBORIDE REINFORCED OXIDE MATRIX COMPOSITES

Composites of particulate TiB₂ in matrices of Y₂o₃-stabilized Zro₂, Y₂o₃ and Al₂o₃ were prepared by vacuum hot pressing in graphite tooling. Results of hot pressing the oxides and the composites are presented. X-ray diffraction and scanning electron microscopy were used to characterize the materials before and after processing. The effects of processing temperature, powder size, pressure and time are emphasized. Chemical reactivity of the diborides with oxygen presents problems which can be minimized by careful control of vacuum and processing sequence. Resultant composite compacts show little evidence of reaction at particle-matrix interfaces.